import java.util.Scanner;

public class h_1 {
    public static void main(String[] args) {
        System.out.print("输入月数：");
        Scanner sc=new Scanner(System.in);
        int mon=sc.nextInt();
        int[] sum=new int[mon];
        if(mon<=2){
            sum[0]=1;
            sum[1]=1;
        }else {
            sum[0]=1;
            sum[1]=1;
            for(int i=2;i<mon;i++){
                sum[i]=sum[i-1]+sum[i-2];
            }
        }
        System.out.println("这个月的兔子数："+sum[mon-1]);
    }
}
